scholarly journals Normal fault interaction caused by coseismic and postseismic stress changes

2001 ◽  
Vol 106 (B9) ◽  
pp. 19391-19410 ◽  
Author(s):  
Concetta Nostro ◽  
Antonio Piersanti ◽  
Massimo Cocco
Keyword(s):  
Normal Fault ◽  
Fault Interaction ◽  
Stress Changes

scholarly journals Coulomb stress transfer and fault interaction over millennia on non-planar active normal faults: the Mw 6.5–5.0 seismic sequence of 2016–2017, central Italy

2017 ◽  
Vol 210 (2) ◽  
pp. 1206-1218 ◽  
Author(s):  
Zoe K. Mildon ◽  
Gerald P. Roberts ◽  
Joanna P. Faure Walker ◽  
Francesco Iezzi
Keyword(s):  
Main Shock ◽  
Central Italy ◽  
Stress Transfer ◽  
Historical Record ◽  
Normal Faults ◽  
Coulomb Stress ◽  
Seismic Sequence ◽  
Fault Interaction ◽  
Slip Rates ◽  
Stress Changes

Abstract In order to investigate the importance of including strike-variable geometry and the knowledge of historical and palaeoseismic earthquakes when modelling static Coulomb stress transfer and rupture propagation, we have examined the August–October 2016 A.D. and January 2017 A.D. central Apennines seismic sequence (Mw 6.0, 5.9, 6.5 in 2016 A.D. (INGV) and Mw 5.1, 5.5, 5.4, 5.0 in 2017 A.D. (INGV)). We model both the coseismic loading (from historical and palaeoseismic earthquakes) and interseismic loading (derived from Holocene fault slip-rates) using strike-variable fault geometries constrained by fieldwork. The inclusion of the elapsed times from available historical and palaeoseismological earthquakes and on faults enables us to calculate the stress on the faults prior to the beginning of the seismic sequence. We take account the 1316–4155 yr elapsed time on the Mt. Vettore fault (that ruptured during the 2016 A.D. seismic sequence) implied by palaeoseismology, and the 377 and 313 yr elapsed times on the neighbouring Laga and Norcia faults respectively, indicated by the historical record. The stress changes through time are summed to show the state of stress on the Mt. Vettore, Laga and surrounding faults prior to and during the 2016–2017 A.D. sequence. We show that the build up of stress prior to 2016 A.D. on strike-variable fault geometries generated stress heterogeneities that correlate with the limits of the main-shock ruptures. Hence, we suggest that stress barriers appear to have control on the propagation and therefore the magnitudes of the main-shock ruptures.

Small scale fault interactions in Southwestern Anatolia as revealed from Seismology & InSAR

2020 ◽  
Author(s):  
Figen Eskikoy ◽  
Semih Ergintav ◽  
Ali Özgün Konca ◽  
Ziyadin Çakır ◽  
Hannes Vasyura-Bathke ◽  
...  
Keyword(s):  
Seismic Activity ◽  
Surface Deformation ◽  
Normal Fault ◽  
Small Scale ◽  
Analysis Tool ◽  
Fault Structure ◽  
Seismic Waveforms ◽  
Stress Changes ◽  
Source Mechanisms ◽  
Eastern Edge

<p>Southwestern Anatolia is part of a N-S extensional regime mainly driven by rollback along the Hellenic subduction zone beneath the Aegean Sea. This seismically active area is controlled primarily by normal fault systems. The fault structures in the region are segmented and in many cases seismic interaction between these segments can be observed.</p><p>2017 seismic activity along the Eastern and Western edges of Gökova Bay. Within the same year, three separate moderate sized (Mw~5) events took place near the town of Ula (Muğla) on the eastern edge of Gökova Bay. One of these earthquakes occurred in April before the Bodrum-Kos earthquake while the other pair occurred in November within two days.</p><p>We relocated all the events that occurred in Ula region in 2017 and remodeled the source mechanisms from regional seismic waveforms by using Bayesian Earthquake Analysis Tool (BEAT). The surface deformations can also be clearly observed from InSAR tracks of both ascending and descending orbits. Because of the large noise margins of the interferograms, atmospheric noise corrections and high resolution DEM data were used.</p><p>Due to temporal and spatial proximity of the two Mw~5 events during the November sequence, InSAR yields only cumulative deformation of the earthquakes. Therefore, we determined the contribution of each event to the cumulative static displacements observed by InSAR data, using the source models from seismic waveforms. The locations and the source mechanisms of the two Mw~5 earthquake are consistent and explain the observed surface deformation.</p><p>Our results imply that these earthquakes occurred on a previously unknown normal fault rather than the southeastern branches of the nearby Muğla Fault as proposed earlier. The results are consistent with the recently mapped fault structure by Akyüz et al. (2018). The November activity implies EW trending, south dipping normal faulting system and the change in the strike direction of the fault on the eastern edge can be clearly seen both InSAR and waveform modelling results of April activity.</p><p>Co-seismic and post-seismic InSAR analysis shows that the seismic activity following the 2017 Mw6.6 Bodrum-Kos propagated from western Gökova Bay where rupture occurred toward east including the Ula region. A long term comparison of seismicity beneath Gökova Bay and Ula region shows that the seismicity in these two regions are temporally correlated. Hence, while the aforementioned moderate sized earthquakes are not directly triggered by the Bodrum-Kos earthquake, increased seismic activity following Bodrum-Kos earthquake shows that the stress changes in these two regions affect each other. The location errors of the events especially the depth errors in the catalogs and the active fault structure in the area cannot be realized without any geodetic or seismic data analysis. This study claims that the interpretations of the moderate size earthquakes should be studied by using multidisciplinary data sets.</p><p>ACKNOWLEDGEMENTS</p><p>This work is supported by the Turkish Directorate of Strategy and Budget under the TAM Project number DPT2007K120610.</p>

Deformed streams reveal growth and linkage of a normal fault array in the Canyonlands graben, Utah

Geology ◽  
2005 ◽  
Vol 33 (8) ◽  
pp. 645-648 ◽  
Author(s):  
Deirdre Commins ◽  
Sanjeev Gupta ◽  
Joseph Cartwright
Keyword(s):  
Normal Fault ◽  
Initial Component ◽  
Length Ratio ◽  
Normal Faults ◽  
Fault Interaction ◽  
Single Fault ◽  
Coupling Fault ◽  
Fault Displacement ◽  
Interaction Phase

Abstract We use the deformation of streams by the growth of active normal faults within the Canyonlands graben of southeastern Utah to constrain the displacement evolution of a fault array during segment interaction and linkage. Coupling fault displacement data with geomorphic analysis of present-day streams and paleostreams permits sequential reconstruction of a three-segment fault array from initial component segments to its final displacement geometry. Our results show that although segment interaction causes enhanced displacement addition at overlap zones, postlinkage displacement accumulation is significant and permits array equilibration to a displacement-length ratio characteristic of a single fault. Evidence of stream disequilibrium indicates that this postlinkage displacement addition was rapid compared to that during the fault interaction phase.

scholarly journals EARTHQUAKE TRIGGERING EFFECT SCENARIOS DURING THE 2014 SEQUENCE IN CEPHALONIA AND 2015 EARTHQUAKE IN LEFKADA BROADER AREAS, IONIAN SEA, GREECE

2017 ◽  
Vol 50 (1) ◽  
pp. 540
Author(s):  
S. Sboras ◽  
A. Chatzipetros ◽  
S. Pavlides ◽  
V. Karastathis ◽  
G. Papadopoulos
Keyword(s):  
Cumulative Effects ◽  
Fault System ◽  
Ionian Sea ◽  
Coulomb Stress Change ◽  
Earthquake Triggering ◽  
Fault Interaction ◽  
Local Complex ◽  
Complex Fault ◽  
Stress Changes ◽  
Complex Distribution

In this paper we defined the local complex fault system of the Cephalonia three strongest earthquakes (Mw6.1, Mw5.3 and Mw6.0) of the January-February 2014 sequence and the Lefkada mainshock (Mw6.4) on November 17, 2015, in order to investigate the fault interaction i) within the 2014 sequence, ii) between the 2014 sequence and the fault that produced the 2015 Lefkada event, and iii) the cumulative effects of all Cephalonia and Lefkada strong events on other neighbouring faults, by calculating the static stress changes. The Coulomb stress change calculations suggest a complex distribution pattern on most of the cases, with only exceptions the F4 fault (Lefkada earthquake), which seems to be barely loaded with stress after the Cephalonia 2014 events, and the “Assos-Skala” fault, which seems to be stress relieved after all Caphalonia 2014 and Lefkada 2015 events.

Sign in / Sign up

Export Citation Format

Share Document